1. Field of the Invention
The present invention is directed to wireless devices that carry out data transmission using at least two or more antennas at each of the sending side and receiving side, and is directed to MIMO wireless transmission system including the above wireless device, and the present invention relates to the configuration of a wireless transmitter receiver suitable for the use environment in which high throughput is required, particularly in wireless transmission when the data size is large, such as in cases of video data and file transfer, and relates to the control method thereof.
2. Description of the Related Art
As the conventional MIMO wireless communication system, a technique to increase the data transmission capacity using a plurality of antennas is disclosed (see G. J. Foschini, “Layered Space-Time Architecture for Wireless Communication in a Fading Environment When Using Multi-Element Antennas,” Bell Laboratories Technical Journal, Vol. 1, No. 2, pp. 41-59, Autumn, 1996). Moreover, there is disclosed a method called an eigen-mode transmission that transmits through one of MIMO transmissions a data on the basis of an eigen value, the eigen value being obtained by singular-value decomposing Channel State Information (CSI) of between transmission and receipt (see J. B. Andersen, “Array gain and capacity for known random channels with multiple element arrays at both ends,” IEEE Journal on Selected Areas Communications, Vol. 18, No, 11, pp. 2127-2178, November 2000). Moreover, there is disclosed a method of determining a modulation method in MIMO-OFDM on the basis of CSI (see Pengfei Xia, Shengli Zhou, and Georgios B. Giannakis, “Adaptive MIMO-OFDM Based on Partial Channel State Information,” IEEE Transactions On Signal Processing, Vol. 52, No. 1, January 2004). FIG. 2 shows the configuration of a conventional MIMO-OFDM wireless device. The MIMO-OFDM wireless device comprises MAC part 11, a baseband part 21, an RF part 30, and an antenna 40.
The MAC part comprises a transmit buffer 101, a Frame Check Sequence (FCS) adder 103, an FCS check part 106, a receive buffer 108, a CSI memory 105, and a MAC controller 104b, and carries out access control. At the time of sending, the MAC part adds an FCS to a data in the transmit buffer to output to the baseband part 21. At the time of receiving, the MAC part carries out error detection of a data outputted from the baseband part 21 and notifies this result to the MAC controller 104b. 
The baseband part 21 comprises an encoder 201, a puncturing part 202, a parser 216 that divides a data into the number of MIMO streams, an interleaver 203, a modulator 204, a transmission MIMO processing part 205, an inverse FFT part 206, a guard-interval adder 207, a parallel-to-serial converter 208, a serial-to-parallel converter 209, a guard-interval remover 210, an FFT part 211, a receive MIMO processing part 212, a demodulator 213, a deinterleaver 214, a parallel-to-serial converter 216, and an error correction part 215.
At the time of sending, a data inputted from the MAC part 11 is outputted to the RF part 30 after being encoded (202, 203), interleaved (204), MIMO processed in the transmission MIMO processing part 205, and OFDM modulated (206 to 208). At the time of receiving, a receive signal inputted from the RF part 30 is demodulated and outputted to the MAC part 11. Blocks 206-208 have the function to OFDM modulate, and blocks 209-211 have the function to demodulate an OFDM signal.
During eigen-mode transmission, a CSI from a sending side to a receiving side is obtained from the receiving side in advance before sending data, and based on a transmission vector obtained by singular value decomposing the CSI the MIMO processing is carried out in the transmission MIMO processing part 205.
In the RF part 30, at the time of sending, a signal inputted from the baseband part 21 is up-converted to a high frequency signal and outputted to the antenna 40. At the time of receiving, a receive signal inputted from the antenna 40 is down-converted and outputted to the baseband part 21. The antenna 40 emits a signal inputted from the RF part 30 into space and outputs a receive signal to the RF part 30.
The MIMO transmission like in the above-described configuration allows for simultaneous transmission of a plurality of streams. As a resend method, there is disclosed a method, wherein after being divided into segments, an error detection code is added to each segment, which is then sent, and at a receiving side the error detection code added to each segment is checked, thereby allowing the presence of an error for each segment to be checked and carrying out the resend in the unit of the segment (see JP-A-2002-538711).